Safety device for low spin projectiles



y 18; 1958 l N. czAJKowsKl 2,825,992

SAFETY DEVICE FOR LOW SPIN PROJECTILES Filed July 2, 1953 2 Sheets-Sheet 2 INVENTOR N. CZAJKOWSKI BY R. W.

ATTORNEYS SAFETY DEVCE FOR LOW SPIN PRUJEQTILES Norman Czajkowski, Takoma Park, Md., assignor to the United States of America as represented by the Secretary of the Navy Application .iuly 2, 1953, Serial No. 365,791

Claims. (Cl. 102-79) (Granted under Title 35, U. S. Code (1952), sec. 266.)

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a fuze adapted for use in a low spin projectile and more particularly to a new and improved safety device for maintaining the fuze in a safe condition during handling and transportation and for arming the fuze in response to centrifugal force.

Heretofore, fuzes of this type employed spring loaded weights and detents pivotally mounted on the fuze casing and disposed 180 apart with respect to each other, the detents being normally forced into locking engagement with the arming rotor by a relatively heavy spring, thus maintaining the fuze in a safe position during handling and transportation.

However, to adapt such devices for use in low spin projectiles it is necessary to reduce the size and tensile strength of the springs and increase the size and weight of the locking detents. Such an arrangement, however, has not proven entirely satisfactory for the reason that upon reducing the strength of the springs and increasing the mass of the detents such devices were extremely sensitive to sudden shock and thus premature arming of `the fuze would often times occur during handling and transportation.

The device of the present invention provides new and improved safety means for a fuze which overcomes all the disadvantages heretofore encountered in prior art devices by providing an arrangement which is devoid of springs and detents, and which will not arm in response to translational forces due to sudden shocks but will'be readily actuated to an armed position in response to a low order of centrifugal force. The invention provides dual arming means for a fuze, particularly adapted for use in a projectile wherein dual firing means are employed for firing the fuze and exploding the projectile upon impact of the projectile with a target. Furthermore, the safety device is provided with a pair of unbalanced arming rotors or elements, each element may be provided with a suitable explosive device such, for example, as a detonator or the like normally out of alignment with a pair of explosive trains arranged in the fuze, the elements being moved from an initial position to an armed position in response to centrifugal force whereupon the detonator's therein are moved into alignment with their respective explosive trains and firing means and thus establishing a pair of continuous explosive trains from the firing means to the booster charge. Movement of the aforesaid rotors or elements to an armed position is restrained by a ball or spherical detent disposed in a pair of helical grooves formed in the rotors respectively for the reason that such forces tend to move the rotors in a direction whereby the helical grooves tend to shear the ball. Thus due to such shearing forces on the ball rotation of the rotors to an armed position is prevented.

An object of the present invention is to provide a new 2,325,9@2 Patented Mar. 18,

and improved safety device for use in a low spin projectile.

Another object of the invention is to provide a new and improved centrifugally actuated safety device for use in a low spin ordnance missile.

VStill another object of the invention is to provide a new and improved safety device for a fuze wherein means are provided for preventing arming of the fuze in response to translational forces due to sudden shocks.

A further object of the invention is the provision of a new and improved safety device for a fuze in which translational forces tend to maintain the device in a safe position and in which the arming means is released for rotation to an armed' position in response to centrifugal torce.

A still further object of the invention is the provision of a new and improved safety and arming device for a low spin projectile wherein translational forces tend to lock the arming rotors thereof in a safe position and centrifugal forces release the arming rotors for rotation to an armed position. V

Otner objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. l is a fragmentary sectional view of a conventional fuze illustrating the manner in which the device of the invention may be arranged therein, the device being shown armed;

Fig. 2 is a top plan view of the device of Fig. l in an unarmed condition, the cover therefor being removed;

Fig. 3 is a view similar to Fig. 2 with the device in an armed condition;

Fig. 4 is a sectional View taken on the line 4-4 of Fig. 2, the arming rotors thereof being shown in elevation; and

Fig. 5 is a sectional view taken on the line 5 5 of Fig. 3.

Referring now to the drawings for a more complete understanding of the present invention and more particularly to Fig. l thereof, the numeral 10 indicates a fragmentary portion of a conventional fuze of the dual con trol type. The fuze comprises a casing 11 having a pair of firing pins 12 releasable and slidably supported in the casing 1l and actuated to a tiring position by a ring plunger 13 as the plunger is moved into tiring engagement therewith in response to impact of the projectile with a target. The fuze is provided with a pair of lead-in charges 14 in communication with the usual booster charge l5 whereupon the booster charge is fired by the lead-in charges.

The fuze casing l1 is provided with a` centrally disposed bore 16 having disposed therein the safety and arming device of the present invention which is generally indicated by the reference character 17. The safety and arming device comprises a casing 18 having a pair of oppositely disposed recesses 19 formed therein. Arranged within each recess 19 is an unbalanced rotor element generally indicated by the reference character 21 and comprising a substantially semicircnlar body 22, each body having a helical groove 23 formed therein and extending substantially half-way around the peripheral surface thereof and in an opposite direction with respect to each other (Figs. 2 and 3). As shown more clearly on Fig. 4 the rotors 2.1 are secured to a pair of pivotally mounted shafts 24 respectively. Each shaft is provided with trunnions 25-26, trunnion 25 being disposed in openings 27 formed in the cover plate 28 and trunnion 26 being disposed in recesses 29 formed in the end wall 31 of the easing 17. By this arrangement the shafts 24 are pivotally mounted between the aforesaid cover plate 28 and end wall 31 and rotatably support the rotors 21 within the recesses 19. The cover plate is secured to the casing 11 by screws orthe like 32 and disposed in abuttingengagement with a shoulder .'33 -'-formedon Veach of the shafts 24 of Figs. 4 and 5 and thus by this-arrangement the rotors 2Z-1aremaintained within the recesses 19.

As shown more clearly onlFig. 47a ball 34 islarranged between the rotors 'Maand-disposed vwithin the helical grooves 23 thereof, the ball being .provided with Voppositely disposed flat `surfaces 35 varranged -in'engagement with corresponding at surfaces 36 formed f on the casing 17, whereupon longitudinal movementof the ball is permitted inV response to rotation ofthe rotor While rotative movement vvthereof is prevented.

Eachrotor 21 has formed thereina bore trfextending-*therethrough and having a detonator '37 arranged therein, the detonators being normally out of alignment with the tiring pins -12 andtheprim'er orllead-in -38 `arranged inthe bottomfwall 31 'of the casing 317. "When the -rotors -have Vbeen =moved 'to an armed position in response -to centrifugal force, Fig. l, thefdetonator 37 ismoved into alignment .with the-lead-in charges -14 and 38 thus a continuous explosive train is 1provided from the-detonators to the booster charge 15. Thus upon impact'the firing pinsare'forcibly driven into=tiring`en gagement with the detonatorsfthereby tiring-the vprimers 38 which in -turn fires the lead-in `14 which initiate the booster charge.

A stoppin 39 is arranged withineach circular-recess 19 andesecured tothe casing 17 in any suitablem'anner such, forexamplefas having a'press tit With a pair of bores 41 respectively, the bores being formed in the'fend wall31. As Amore clearly shown on Fig. 3, thepins'39 limit lthe movementof rotors '2l as kthe 'rotors are rotated in response to centrifugal'force and theshoulders 42 thereon engage the stop pins. rotor is in an armedposition as'shown in Fig. l.

Bythe aforesaid^safety device 'arrangement itwill be understood that the forces dueto sudden shock to which the device may be subjected during handling and transportation are translational forces and thus since therotors are constructed andarranged to be actuated to an armed position only in `a central force field, obviously Vtranslational forces willnot cause the device to arm. For example, translationalforces tend to rotate the rotors in the same 'direction whereby 'the helical grooves tend to shear the ball and'fthus due to such shearing forces on the ball, the rotors are'locked and-maintained in an initial safe position. However, in response to a central force eld such, for example, `as lproduce by the spin of a projectile the nnbalanced'rotors are rotated in opposite directions whereby no shearing forces are-appliedv to the ball and thus the ball willride -freelynpwardly in the helical grooves thereby to release and permitthe Vrotors to be readily rotated to an armed position.

The operation of the -fuze safety, device'in a spinprojectile will be made more apparent by the following description. Initially the rotor safe-ty elements 21 are arranged in casingl as shown in Fig. 2. In this initial position the detonators 37 disposed in the rotor elements `are out of alignment with tiring pins 12 andprimers 38, and the fuze is thereby in an unarmed condition. Upon launching of the spin-projec-tile, the rotor elements are subjected to a centrifugal force which causes the rotors to rotate about the yshaft 24. Due to the unbalanced design of these rotors, resulting from their peripheral coniiguration and cut-out portions, the center of gravity of each rotor is located in a region between the bore 30 and the shaft 24. As is shown in'Fig. 2, the'center of gravity of each rotor is Ylocated on `oppositesides of the shaft, and therefore a centrifugal force acting .on each rotor will develop a rotational torque in opposite directions. Due to the design ofthe helical ,groove 23 of each rotor, rotation in opposite directions by the Arotors will enable .detent .ball 3.4,to Vride fully in the grooves, and the rotors will continue their rotation until contact with stop pins 39foccurs, as shown in Fig. 3. Upon contact with the stop pins, the detonators 37 are aligned with the primers and firing pins and the fuze is in an armed condition, as shown in Fig. l. Upon con- 'tactof the projectile with a target, lthe fring plunger 13 of the .fuze is driven .rearward into contact with .the tiring pins forcing them into contact with the detonators and actuating them. Actuation of the detonatorvtires the lead in charge, or primer, 14 whereupon the booster charge 15 is initiated.

While the aforesaid safety devicejof the present invention has been shown in connection With a fuze em ploying dual tiring means Yfor ring the -fuze andex ploding the projectile it will be understood that, if de sired, the device may be employed with a fuze employing single firing means, andif such is fthe -case f only oneY of the rotors 21 would be-'providedwith Ia detonator orfexplosive device.l Furthermore, while the rotors'have'been described as being provided Vwith detonators -it will be understood that, if `desired,the rotors maybe provided with any other Vsuitable -explosivedevices such, for example,-asaprimerinitiator, lead-in charge or the like whereupon aniexplosivetrain 'may be completed to-arm the fuzewhenthetrotors haverbeenrotated to an armed position.

-In viewof 4theforegoing, .it will `be apparent that the present invention provides a new and improved safety andarmmg means for alowspin ordnance missile wherein vmeans-responsive'totranslational-forces due to sudden shocks tend -to-'lock the :arming rotors in a safe position and to release the rotors for rotationto Van armed posi- WhenV this occurs the tion in response tofcentrifugal force.

Obviously many `modifications and variations of the presentinventionfare'possible in the light of the'above teachings. YItfis .therefore to be understood-that within the scopeeof the-appended claims theinvention may be practiced otherwise than aslspecically described.

What is claimed as-new and desired to be secured by LettersfPatent in the YUnited vStates is:

v-1. A'safety device for alowspin-fuzed pr-ojectile comprising a casing, a pair of unbalanced rotors having helical groovesformedthereon supported Within said casing lformovenient: toan armed'fposition `by 4centrifugal force, and a spherical Ydetent/disposed between said pair of rotors in said Agroovesforrestraining the movement lvof therotorstosaid"armed 'position in response to trans lationalforcesrand for lreleasing therotors formovement to r`said armed `position'by centrifugal force Vthereby 'to arm'said fuzedprojectile.

'2. ,A safety -device lfor `a vlow spin ordnance missile f' comprisinga casing,a 'pair of'recesses in said casing, a

,pair'of'centrifugally actuated rotorsl disposed within said recesses respectively, meanssecured to said rotors and pivotallymounted on said casing'for rotatably supporting the rotors within said recesses, a pair of helical .grooves arranged within .said rotors respectively, and a ball disposed between said rotors and arranged within saidgrooves for locking and maintaining the rotors in a safe position when the missile is subjected to translational forces and .for releasing the rotors for rotation to an armed position in'responseto centrifugal force.

3. A safety deviceffor 'a low-spin projectile comprising 'a casing, agpair of recesses in said casing, a pair of cen- 'trifugally actuated rotors disposed Within said recesses respectively, Ameanss'ecnrel to vsaid `casing formaintaining the rotors'within saidrecesses, Va shaft vsecured to each 'of the Vrotors 'and pivotallymounted on the casing for rotatably supporting 'the .rotors within said recesses, a pair .of helicaljgrooveslarranged Within therotors respectively, a ball disposed'between and arranged lwithin said 5 force, said ball being adapted to release the rotors for rotation to an armed position in response to centrifugal force, and means on the casing for preventing further movement of the rotors as the rotors move to said armed position.

4. In a safety and arming device for a fuze adapted for use in a low spin projectile, the combination, a casing supported by said projectile, 4an explosive charge arranged within the casing, a pair of firing devices slidably supported within the casing, a pair of rotors having helical grooves formed thereon arranged within the casing for movement from a safe position to an armed position by centrifugal force, means including a spherical detent disposed between and within said grooves of said rotors for maintaining the rotors in said safe position when the device is subjected to translational forces and for releasing the rotors for rotation to said armed position in response to said centrifugal force, a pair of explosive devices arranged in said rotors respectively and moved into alignment with the ring devices as the rotors move to said armed position, and means responsive to impact of the projectile with -a tar-get for forcibly driving the firing devices nto ring engagement with said explosive device thereby to re t-he explosive device and explode the explosive charge.

5. In a safety and arming device for a fuze adapted for use in a low spin projectile, the combination, a housing supported by said projectile, an explosive charge 'arranged within the housing, a pair of firing devices slidably supported within said housing, a casing arranged wi-thin said housing, a pair of centrifugal actuated rotors disposed within said casing for movement from a safe position to an armed position by centrifugal force, means secured to said rotors and pivotally mounted on the casing for rotatably supporting the rotor therein, a pair of helical grooves larranged within Athe rotors respectively, a spherical detent disposed between said rotors and arranged Within said grooves for locking the rotors in said safe position when the device is subjected to translational forces and for releasing the rotors for rotation to said armed position in response to said centrifugal force, a pair of detonators arranged in the rotors respectively and moved into alignment with said ring devices as the rotors move to said armed posi-tion, and means responsive to impact of the projectile with a target for forcibly driving the firing devices into firing engagement with said detonator thereby to re the detonator and explode the explosive charge.

References Cited in the le of this patent UNITED STATES PATENTS 1,561,687 Brayton Nov. 17, 1925 1,999,747 Aragone Apr. 30, 1935 2,564,797 Thompson Aug. 2l, 1951 FOREIGN PATENTS 93,566 Austria July 10, 1923 837,467 France Nov. 12, 1938 

